It would seem an improvement item for the F-22, if it were to be restarted, is the stealth cladding that has been used. I believe it contributes the most to overall maintenance costs for the aircraft. Perhaps that used on the F-35 would be better.
My understanding is that a lot of the F-35 stealth cladding tech is being applied to F-22 right now. I'm confident that that tech will continue to improve. For example the B-21 program will very likely make strides in that area and I'd venture that at least some of that tech will be incorporated in F-35 as they come off the assembly line, and likely be back fitted to ones already in service.
Further on the subject of an F-22 line re-open: I would think that an F-22N (for "new") would leverage far more than F-35 stealth cladding tech. I would think they would leverage F-35 avionics tech and maybe even engine tech. Both are superior in the F-35 relative to the F-22. And if done right, they could be back fitted to the F-22As and maybe even give the F-22 a much better air-to-ground capability in much the same way that F/A-18 tech applied to the F-15C/D resulted in the F-15E.